The use of modular plugs and jacks for data transmission is common. Plugs are attached to ends of an electrical cable connecting two electronic devices such as switches or routers in data centers or computers in offices. The cables have multiple conductors, or wires. For Ethernet protocol connectivity, typically eight wires are used. While the cable is terminated by plugs, the electronic equipment must have jacks corresponding to the plugs. Plugs and jacks are designed to be intermateable to provide both mechanical and electrical coupling. Mechanical dimensions of the plugs and jacks, and their interface therebetween, are governed by international standards. In the case of the connectors employed in the Ethernet signal transmission the governing standards are International Electrotechnical Commission standards 60603-7 series.
From the transmission point of the jacks, cable and plug represent components of a channel. The channels and corresponding components performance are referred as classes and categories specified in the IEC/ISO 11801 standards shown in the following table:
ISO/IEC Cable/connector Freq. max.11801categoryCharacterizationClass C3    16 MHzClass D5e 100 MHzClass E6   250 MHzClass EA6A 500 MHzClass F7   600 MHzClass FA7A1000 MHzClass I8.12000 MHz
Common mechanical connector configurations allow the utilization of the existing networking equipment through a feature called auto-negotiation. During the auto-negotiation process, both connected devices assume master-slave relations and agree on the maximum speed for data to be transmitted.
The channels must be able to support the Ethernet protocols and may affect the auto-negotiation. If any component is designed for the older Ethernet speeds, it will force the newer and faster networking equipment to run below its intended speed.
In order to support the 40 Gigabit per second Ethernet protocol, the Class I channel with category 8.1 connectors are required.
The modular plugs connected to the cables can be plugged into jacks disposed within the various generations of the Ethernet equipment. In such cases, the modular plugs are configured to work with equipment of relatively slow speed (i.e. 100 MHz) and also at the other extreme with the highest speed equipment (i.e. 2000 MHz).
A conventional objective of plug design is to assure safe electrical isolation. For example, the equipments should withstand 1000 VDC between adjacent contacts and 1500 VDC between all the contacts and shields without shorting flash-over.
In current practice, the common RJ45 mechanical interface described in the IEC6003-7-1 standard allows connections between 40 GbE and lower speed equipment. However, there are no known modular plugs that work in the wide spectra from 100 to 2000 MHz without causing some degradation of the signals. Plugs mated with corresponding jacks form a mated connector pair, within which the electromagnetic signals travel from the equipment side to the cable side and vice versa.
Ethernet protocols divide the electromagnetic signals into four streams. These streams are transmitted over the same cable. Thus, with a mated connector pair, there are four streams or channels of signals operating simultaneously. The unwanted interaction of these signals is called near end cross talk (or NEXT). The NEXT must be minimized to allow substantially error-free transmission of data. The most common method of reducing NEXT is through compensation. Compensation can be provided by creating signals of similar amplitude but opposite polarity from the NEXT signals that are inherently present at the interface between the jack and the plug. Thus, the compensation NEXT will cancel out the original NEXT.
Signal degradation at high frequencies is caused by one or more of several potentially mutually dependent issues. Introducing compensation far away from the interface may cause an unpredictable phase shift of electromagnetic signals traveling within the jack and plug connection. The plug contact blades have high intrinsic self-inductance and uncontrolled and relatively low capacitance between adjacent contacts. Known designs also do not allow for control of the interaction of the cable pairs within the plug. The distance between the cable terminations and the contacts is overly long in existing designs. Finally, most of the existing plug designs attempt to provide easy termination in the field at the expense of transmission performance.
It would accordingly be desirable to provide a mating interface to a modular jack in accordance with existing mechanical and category 8.1 electrical standards and operate at a wide range of frequency spectra from 100 MHz to 2000 MHz and above.
It would further be desirable to reduce the phase shift between the primary compensation and contact interface.
It would further be desirable to mate such an apparatus with lower category connectors with corresponding degradation of their properties.
It would further be desirable to terminate the apparatus to cables in the field using hand tools, or alternatively to cables at the factory locations, in either event using essentially the same components.
It would further be desirable to provide the apparatus with a configuration that can be easily manufactured and at low cost, for example minimizing the number of plug parts and internal components needs. It would particularly be desirable to require no additional discrete electronic components such as capacitors, inductors and/or resistors.
It would further be desirable to control cable pairs within the plug and further provide isolation of said pairs by an air gap that is integral to the primary printed circuit board.
It would further be desirable if the primary printed circuit board controlled the connector electrical signal properties by means of controlled impedance.
It would further be desirable if the compensation is provided by an independent, secondary rigid printed circuit board.
It would further be desirable if the electrical signal properties are controlled by the intrinsic characteristics of the primary and secondary printed circuit boards, particularly without relying on secondary tuning of these boards.
It would further be desirable for the cable contacts to have low self-inductance and high capacitive coupling.
It would further be desirable to terminate cables within a wide range of wire gages; both stranded and solid conductors from AWG 22 to AWG 28.